It is known to a person skilled in the art in the food industries that the volatile compounds present in products contribute to their savour. Flavourings are generally mixtures of aromatic substances mainly comprising volatile molecules. The volatility and/or the lability of certain molecules present in food products can be responsible for a variation in the flavours and taste of foods over time. Therefore, the food industries often choose to increase the concentration of these flavourings in order to compensate for their degradation or disappearance over time. As some of these compounds are expensive, the use of large quantities of flavourings presents however a problem regarding cost.
By “flavouring” or “aromatic substance” is meant a compound imparting an odour or taste to the composition to which it is added. There can be mentioned as examples the spice oleoresins, alliaceous flavours essential oils; botanical extracts; botanical flavouring extracts and protein hydrolysates.
The flavouring can be in the form of an oil, non-aqueous solution or emulsion.
The term “labile” describes unstable compounds the interaction of which with the environment leads to degradation, loss of function or destruction. Thus, certain molecules can have sensitivity to external agents such as heat, light, atmospheric oxygen or humidity. This sensitivity can be responsible for a degradation or conversion of the molecule to an undesirable compound from the stage of formulation or during the production or storage of the food products, thus making them unfit for consumption.
Therefore, these labile compounds must be packaged in an appropriate manner in order to guarantee both                good preservation without alteration of their organoleptic properties and        their availability for flavouring the food in which they are present.        
Numerous encapsulation, micro-encapsulation or trapping methods have been developed in order to protect the volatile and/or labile molecules of flavouring during its production, during the process of manufacture of the food product or during the storage and use of the latter.
Similar problems are encountered in the pharmaceutical field where encapsulation is frequently used to solve problems of lability, solubilization of hydrophobic compounds, bioavailability or bitterness of certain active principles. Encapsulation also allows slow and controlled release of the active principles. Of course, the encapsulation agents must be biocompatible and bioresorbable.
The active principle to be encapsulated can be incorporated in the encapsulation agent as it is, i.e. in its solid or liquid native form. It can also be incorporated in the form of an emulsion or aqueous suspension. This aqueous emulsion can be obtained by emulsification of the pure active principle or of the active principle previously dissolved in an appropriate oil of the silicone oil type for example.
The most used encapsulation agents are generally of osidic nature: wheat, potato, maize starches and their derivatives (modified starches, dextrins, maltodextrins, glucose syrups, dextrose, polyols etc.), gum arabic which is the most used encapsulation support, saccharose, cyclodextrins, cellulose and its derivatives, alginate type gums, agar-agar or carragheenans.
In all the methods of protection by encapsulation, the encapsulation agent must have the following characteristics:                not modify the characteristics of the encapsulated products,        be odourless,        have a low viscosity, even at a high concentration,        stabilize the emulsion while drying,        be non-toxic and edible,        have a low hygroscopicity,        have an ability to progressively release the encapsulated active material and        have a low cost.        
Various encapsulation techniques exist, chosen depending on the intended purpose of the product to be encapsulated or its use.
A first system, known as a matrix or coating system comprises the inclusion of a substance in a solid matrix by occlusion or adsorption. This encapsulation is carried out for example by spray drying or dispersion drying, during which the flavourings are emulsified in a suitable continuous phase, and then spray dried in a hot draught. The encapsulation agents most used for this technique include gum arabic, maize, wheat, tapioca or potato maltodextrins, dextrose, lactose and gelatin. Other technologies are also described such as cold spray-drying, granulation, extrusion or coating in a fluidized bed.
A second system known as membrane encapsulation consists of surrounding the compounds to be encapsulated with a continuous film of polymers, lipids, glucides or polysaccharides. The techniques used are for example coacervation, co-extrusion or the use of liposomes.
The extrusion technique is described in the U.S. Pat. No. 6,187,351 which describes the use of different polymers, which include maize, rice, wheat or tapioca starches and maltodextrins.
The document EP 1,304,044 describes the use of sugars, modified starches, maltodextrins and other polymers in combination with a cellulose derivative.
The maltodextrins and glucose syrups are conventionally obtained by acid and/or enzymatic hydrolysis of starch. They can be used as encapsulation agents and contain a complex mixture of linear and branched saccharides. Referring to the regulatory status, the maltodextrins have a dextrose equivalent (DE) of 1 to 20. The glucose syrups have a DE greater than 20.
The quality of an encapsulation can be evaluated for example by measuring the encapsulated compound protection by the encapsulation agent against oxidation.
It has thus been noted that, during the limonene encapsulation by maize maltodextrins or maize glucose syrups of varying DE, the oxidation of the flavouring over time decreased when the DE of the encapsulation agent increased (Reineccius G. A. (1988) “Spray drying of Food Flavors” In “Flavor Encapsulation,” eds. Sara J. Risch and Gary A. Reineccius, chap. 7, pp: 55-66.). In other words, the protection of a flavouring by encapsulation is better with maize glucose syrups (with a significant DE) than with maize maltodextrins (with a low DE). Moreover, encapsulation is better with the most highly hydrolyzed maize maltodextrins.
Moreover, a study of the quality of encapsulation by maltodextrins of various vegetable origins has shown that, when the DEs of maize, rice, tapioca or potato starch derivatives (maltodextrins, glucose syrups) increase, the protection of the encapsulated compounds vis-à-vis oxidation increases, irrespective of the vegetable origin of the starch. Moreover, the maize, tapioca or rice maltodextrins with a high DE, or even the wheat, tapioca or rice glucose syrups are encapsulation agents allowing better protection against oxidation Onglett G. E., Gelbman P., and Gary A. Reineccius (1988) “Encapsulation of Orange Oil: Use of Oligosaccharides from α-Amylase Modified Starches of Maize, Rice, Cassava, and Potato.” In “Flavor Encapsulation,” eds. Sara J. Risch and Gary A. Reineccius, chap. 4, pp: 29-36). These observations have been adopted as a general principle.
The prior art also describes the use of cyclodextrins, dextrins or amylose as encapsulation agents.
These molecules form inclusion complexes with the molecules to be encapsulated which are trapped either between molecules of the encapsulating agent forming a crystalline organization, or in a cavity formed by a structure of the encapsulation molecule. The techniques mainly used with these encapsulation agents are kneading, crystallization and lyophilization.
In the food sector, these techniques advantageously allow to obtain water-soluble hydrophilic powders containing hydrophobic compounds or an increase in the thermal stability of the flavourings during cooking. Due to their reversible character they allow good complexation in concentrated medium and the release of the encapsulated molecules in diluted aqueous medium or after contact with saliva.
β-cyclodextrin is the most used of the cyclodextrins and the most economical to produce. However, the use of cyclodextrins is highly regulated.
In order to be free from these regulatory constraints, the development of the use of amylose as an encapsulation agent forming inclusion complexes has been envisaged. Amylose is organized in helices with a hydrophilic external surface due to the presence of hydroxyl groups and with a hydrophobic internal surface due to the presence of hydrogen atoms. This helical structure confers the amylose the necessary characteristics for the encapsulation of active principles or flavourings.
The use of pure amylose cannot however be envisaged on an industrial scale due to their great propensity to crystallization or retrogradation.
The use of starches rich in amylose (starches containing more than 50% amylose) for encapsulation, also involves various constraints, since they require very strict conditions of preparation and use. Indeed, these starches retrograde rapidly due to their richness in amylose. Moreover, they require very high cooking temperatures, of the order of 120° C. In order to prevent retrogradation phenomena, the encapsulation must be carried out at high temperatures of the order of 90 to 100° C. Now at these temperatures, the labile and/or volatile compounds are degraded or evaporate. In order to reduce their retrogradation temperature, starches containing more than 50% amylose are generally modified by fixation of chemical groups. These starches are named stabilized.
By “stabilization” of starch is meant all the operations known to a person skilled in the art intended to slow down or check the retrogradation of the starch. The stabilization is obtained by substitution of the hydroxyl functions of the starch, by esterification or etherification. It can also be obtained by oxidation. These stabilization treatments are in particular hydroxypropylation, acetylation, phosphation and oxidation.
The stabilization of amylose-rich starches allows to reduce their retrogradation temperature to 50-60° C. but reduces their ability to form inclusion complexes.
In the particular context of the encapsulation of flavourings of alcoholic liquids such as wine, the document EP 820 702 describes the use of a pea starch as an encapsulation agent by spray-drying or by lyophilization. Pea starch is described as imparting to the encapsulation qualities of retention of the flavourings without retention of alcohol. The presence of long polysaccharidic chains is the characteristic essential for the pea starch to be able to encapsulate the flavourings according to the described invention. In fact, this document EP 820 702 excludes the use of a hydrolyzed pea starch and quite particularly the use of pea maltodextrins and glucose syrups as encapsulation agents. According to this document, these hydrolyzed forms of starch comprise sugar chains which are too short to allow encapsulation.
The purpose of the present invention is to extend the range of encapsulation agents and encapsulation techniques which can be used with the same encapsulation agent. The encapsulation agent must be easy to use, non-toxic and allow a controlled release of the encapsulated compound.
The present invention is based on the discovery, contrary to the conclusions of EP 820 702, that certain leguminous starches hydrolysis products, and in particular pea, were excellent encapsulation agents of hydrophobic substances, in particular aromatic substances.
The Applicant, during tests aimed at proposing novel encapsulation agents, has surprisingly noted that the maltodextrins and glucose syrups derived from leguminous starches had an atypical behaviour, different from that of the equivalent products derived from maize, rice, wheat or tapioca starches, which were characterized by the fact that their power of protection of the encapsulated compounds vis-à-vis oxidation was as much better as their DE was lower.
The Applicant has moreover noted that the maltodextrins and/or glucose syrups derived from leguminous protected certain encapsulated compounds against oxidative degradation better than the corresponding products derived from other starches.